Nitrate is linked to chronic human illness and to a variety of environmental problems, and continues to be a contaminant of concern in soils and natural waters. Improved methods for nitrate abatement, thus, are still needed. The purpose of this study was to assess the potential for redox-modified, iron-bearing clay minerals to act as nitrate decontamination agents in natural environments. The model clay mineral tested was ferruginous smectite (sample SWa-1) exchanged with either sodium (Na+) or polydiallyldimethylammonium chloride (poly-DADMAC). Structural iron (Fe) in SWa-1 was in either the oxidized or reduced state. Little nitrate uptake was observed in the Na+-SWa-1, which was attributed to coulombic repulsion between the basal surfaces of the smectite and the nitrate anion. The addition of the DADMAC to the SWa-1 reversed the electrostatic charge manifested at the smectite surface from negative to positive, as measured by the zeta (ζ) potential. The positively charged poly-DADMAC-SWa-1 yielded high nitrate uptake due to coulombic attraction in both the oxidized and reduced states of the Fe in the SWa-1. The presence of reduced structural Fe(II) in the positively charged poly-DADMAC-SWa-1 enabled a chemical reduction reaction with the nitrate to produce nitrite. The amounts of nitrite found in solution, however, failed to account for all of the Fe(II) oxidized, so other N reduction products may also have formed or perhaps nitrite was also present in the adsorbed phase. The effects of other complexities, such as polymer configuration at the surface, also need further investigation. The results do clearly establish abiotic nitrate reduction to nitrite and possibly other reduction products. The combination of bacterial activity in soils and sediments, which is known to reduce structural Fe in smectites, and the abundance of organic cations in soil organic matter creates an environment where reversed-charge smectite could exist in nature. This represents a potentially effective system for mitigating harmful effects of nitrate in soils, sediments, groundwater, and surface water.

Fructose (C6H12O6), also known as levulose, is a hexose. Chronic consumption of fructose may be associated with increased intrahepatic fat concentration and the development of insulin resistance as well as an increase in the prevalence of nonalcoholic fatty liver disease and hyperlipidemia during pregnancy. Despite the existence of many studies regarding the consumption of fructose in pregnancy, its effects on fetuses have not yet been fully elucidated. Therefore, the objective of this study was to evaluate the genetic and biochemical effects in offspring (male and female) of female mice treated with fructose during pregnancy and lactation. Pairs of 60-day-old Swiss mice were used and divided into three groups; negative control and fructose, 10%/l and 20%/l doses of fructose groups. After offspring birth, the animals were divided into six groups: P1 and P2 (males and females), water; P3 and P4 (males and females) fructose 10%/l; and P5 and P6 (males and females) fructose 20%/l. At 30 days of age, the animals were euthanized for genetic and biochemical assessments. Female and male offspring from both dosage groups demonstrated genotoxicity (evaluated through comet assay) and oxidative stress (evaluated through nitrite concentration, sulfhydril content and superoxide dismutase activity) in peripheral and brain tissues. In addition, they showed nutritional and metabolic changes due to the increase in food consumption, hyperglycemia, hyperlipidemia, and metabolic syndrome. Therefore, it is suggested that high consumption of fructose by pregnant female is harmful to their offspring. Thus, it is important to carry out further studies and make pregnant women aware of excessive fructose consumption during this period.

There is increasing evidence for the health benefits of dietary nitrates including lowering blood pressure and enhancing cardiovascular health. Although commensal oral bacteria play an important role in converting dietary nitrate to nitrite, very little is known about the potential role of these bacteria in blood pressure regulation and maintenance of vascular tone. The main purpose of this review is to present the current evidence on the involvement of the oral microbiome in mediating the beneficial effects of dietary nitrate on vascular function and to identify sources of inter-individual differences in bacterial composition. A systematic approach was used to identify the relevant articles published on PubMed and Web of Science in English from January 1950 until September 2019 examining the effects of dietary nitrate on oral microbiome composition and association with blood pressure and vascular tone. To date, only a limited number of studies have been conducted, with nine in human subjects and three in animals focusing mainly on blood pressure. In general, elimination of oral bacteria with use of a chlorhexidine-based antiseptic mouthwash reduced the conversion of nitrate to nitrite and was accompanied in some studies by an increase in blood pressure in normotensive subjects. In conclusion, our findings suggest that oral bacteria may play an important role in mediating the beneficial effects of nitrate-rich foods on blood pressure. Further human intervention studies assessing the potential effects of dietary nitrate on oral bacteria composition and relationship to real-time measures of vascular function are needed, particularly in individuals with hypertension and those at risk of developing CVD.

This study aims to develop an in vitro co-culture system of in situ goat preantral follicles with bone marrow-derived mesenchymal stem cells (BM-MSC), evaluating the influence of these cells on follicular growth, rate of activation and morphologically normal follicles. Fragments of ovarian cortex were cultured for 1 or 7 days in the presence of BM-MSC (BM-MSC+) and absence of BM-MSC (BM-MSC−). Histological sections of the fragments were analysed and data were obtained regarding morphological classification, survival rate of morphologically normal follicles and rate of follicular activation. Culture medium on days 1 and 7 was also sampled for nitrite concentration and reduced glutathione activity. There was a reduction (P < 0.05) in the percentage of morphologically normal follicles in the BM-MSC+ compared with the fresh control only on the seventh day of culture. When comparing treatments, on the seventh day of culture, a higher rate of morphologically normal preantral follicles was observed in BM-MSC+ (P < 0.05). In both treatments, primordial and developing follicle rates were similar to the fresh control (P > 0.05). When comparing treatments with each other, as well as with the fresh control, no differences were observed in follicular diameter (P > 0.05) or nitrite concentration (P > 0.05). The concentration of reduced glutathione was lower on the seventh day of co-culture in both treatments (P < 0.05). In conclusion, co-culture had no influence on follicular or oocyte development. However, it was critical to maintain the survival of preantral follicles during 7 days of culture.

In this work, a N-doped CsTi2NbO7@g-C3N4 (NTCN) heterojunction nanocomposite was synthesized by a simple one-step calcination method. The as-prepared samples were characterized by means of X-ray diffraction patterns, scanning electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, and Fourier transformed infrared spectroscopy. The results showed that g-C3N4 was formed both on the surface and within the interlayers of CsTi2NbO7, in which CsTi2NbO7 was in situ doped by nitrogen atoms to form N–CsTi2NbO7. The NTCN composite displayed higher electrocatalytic activity toward the detection of nitrite than pure CsTi2NbO7 and g-C3N4. The main reasons could be attributed to the synergistic effects of morphology engineering, N-doping, and layered heterojunction. The NTCN-based electrochemical sensor expressed a good linear relationship range from 0.0999 to 3.15 mmol/L with a detection limit of 2.63 × 10−5 mol/L. The good recovery, stability, and reproducibility of this biosensor showed the potential application in environmental monitoring.

Dietary nitrate has been shown to increase nitrate/nitrite levels and decrease blood pressure (BP) in multiple populations. There are few reports among hypertensives and these reports have provided conflicting evidence. We aimed to assess the effect of daily nitrate compared with placebo in subjects with uncontrolled hypertension (HTN). On day 0, hypertensives wore an ambulatory BP monitor (ABPM) for 24 h and blood was taken. Subjects were then randomised to 7-d nitrate-rich beetroot juice (NO3−) (12·9 mmol nitrate) followed by 7-d nitrate-depleted beetroot juice (0·5 mmol nitrate) or vice versa. ABPM and blood were assessed before and after both conditions. In all, twenty subjects with treated yet uncontrolled HTN entered and completed the trial (mean age=62·5 years, mean BMI=30·7 kg/m2). Baseline BP was 137/80 (sd 7/7) mmHg. Dietary nitrate was well tolerated and resulted in significantly increased plasma nitrite (P=0·0004) and decreased 24-h systolic BP and diastolic BP compared with placebo (−8 mmHg; P=0·012 and −4 mmHg; P=0·018, respectively). Our results support the existing data suggesting an anti-hypertensive effect of dietary nitrate in treated yet uncontrolled hypertensives. Targeted dietary strategies appear promising contributors to BP control.

CVD is the leading cause of death worldwide, a consequence of mostly poor lifestyle and dietary behaviours. Although whole fruit and vegetable consumption has been consistently shown to reduce CVD risk, the exact protective constituents of these foods are yet to be clearly identified. A recent and biologically plausible hypothesis supporting the cardioprotective effects of vegetables has been linked to their inorganic nitrate content. Approximately 60–80 % inorganic nitrate exposure in the human diet is contributed by vegetable consumption. Although inorganic nitrate is a relatively stable molecule, under specific conditions it can be metabolised in the body to produce NO via the newly discovered nitrate–nitrite–NO pathway. NO is a major signalling molecule in the human body, and has a key role in maintaining vascular tone, smooth muscle cell proliferation, platelet activity and inflammation. Currently, there is accumulating evidence demonstrating that inorganic nitrate can lead to lower blood pressure and improved vascular compliance in humans. The aim of this review is to present an informative, balanced and critical review of the current evidence investigating the role of inorganic nitrate and nitrite in the development, prevention and/or treatment of CVD. Although there is evidence supporting short-term inorganic nitrate intakes for reduced blood pressure, there is a severe lack of research examining the role of long-term nitrate intakes in the treatment and/or prevention of hard CVD outcomes, such as myocardial infarction and cardiovascular mortality. Epidemiological evidence is needed in this field to justify continued research efforts.

Dietary nitrate is mainly obtained from vegetables, especially green leafy vegetables and beetroot. As a result of early research, dietary nitrate is currently viewed as a contaminant linked to increased risks of stomach cancer and methaemoglobinaemia. Consequently, nitrate levels are restricted in certain vegetables and in water supplies to ensure exposure levels remain below an acceptable daily intake of 3·7 mg/kg per d. The average nitrate intake in the UK is approximately 70 mg/d, although some population groups, such as vegetarians, may consume three times that amount. However, recent studies in the last decade suggest that dietary nitrate can significantly reduce systolic blood pressure via the nitrate–nitrite–NO pathway. A small, downward shift in systolic blood pressure across the population could significantly reduce the incidence of hypertension and mortality from CVD such as stroke. Interestingly, vegetarians tend to have lower levels of blood pressure than omnivores and epidemiological studies suggest that vegetarians have lower risks of CVD. Recent evidence is mainly focused on the acute effects of dietary nitrate supplementation and there is a lack of data looking at the chronic effects of high nitrate consumption in humans. Nevertheless, due to potential health benefits, some authors are recommending that nitrate should be considered as a nutrient necessary for health, rather than as a contaminant which needs to be restricted. This review will discuss the emerging role of dietary nitrate in the control of blood pressure and whether there is sufficient evidence to state that nitrate is a ‘new’ nutrient.

Few studies have examined the impacts of ground water quality on residential property values. Using a unique data set of well tests, we link residential real estate transactions to home-specific contamination and conduct a hedonic analysis of sales in Lake County, Florida, where pollution concerns relate primarily to agricultural run-off. We find that recent testing and contamination of ground water there correspond to a 2–6 percent depreciation in home values, an effect that diminishes over time. Focusing on nitrogen-based contamination, we find that prices decline mainly when concentrations exceed the regulatory health standard, suggesting as much as a 15 percent depreciation at levels twice the standard.

A number of vegetables have a high nitrate content which after ingestion can be reduced to nitrite by oral bacteria, and further to vasoprotective NO endogenously. In the present study, two separate randomly controlled, single-blind, cross-over, postprandial studies were performed in normotensive volunteers. Ambulatory blood pressure (BP) was measured over a 24 h period following consumption of either four doses of beetroot juice (BJ), 0, 100, 250 and 500 g (n 18), or three bread products, control bread (0 g beetroot), red beetroot- and white beetroot-enriched breads (n 14). Total urinary nitrate/nitrite (NOx) was measured at baseline, and at 2, 4 and 24 h post-ingestion. BJ consumption significantly, and in a near dose-dependent manner, lowered systolic BP (SBP, P < 0·01) and diastolic BP (DBP, P < 0·001) over a period of 24 h, compared with water control. Furthermore, bread products enriched with 100 g red or white beetroot lowered SBP and DBP over a period of 24 h (red beetroot-enriched bread, P <0·05), with no statistical differences between the varieties. Total urinary NOx significantly increased following the consumption of 100 g (P < 0·01), 250 g (P <0·001) and 500 g BJ (P <0·001) and after red beetroot-enriched bread ingestion (P <0·05), but did not reach significance for white beetroot-enriched bread compared with the no-beetroot condition. These studies demonstrated significant hypotensive effects of a low dose (100 g) of beetroot which was unaffected by processing or the presence of betacyanins. These data strengthen the evidence for cardioprotective BP-lowering effects of dietary nitrate-rich vegetables.

Both the California chaparral species, Emmenanthe penduliflora Benth. (Hydrophyllaceae), and a tobacco native to the Great Basin Desert of south-western Utah, Nicotiana attenuata Torr. ex Wats. (Solanaceae), germinate in response to component(s) of wood smoke. Nitrogen oxides (NO and NO2), in amounts produced by a fire, have been proposed to be germination signals for E. penduliflora. We examined the germination response of dormant seeds of E. penduliflora and N. attenuata to aqueous solutions of smoke adjusted to different pHs, and two NO donors [sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP)]. The smoke solutions, at pH 4 or 5, induced the maximum germination response. Aqueous solutions of SNP and SNAP, releasing NOx as high as 42 μM, had no effect on germination. Additionally, NO2– could not be detected in aqueous smoke extracts derived from combusted cellulose or wood. Therefore, unidentified cellulose combustion factors, rather than NOx, are likely to be the ecologically relevant germination signals.

A commercial liquid smoke (LS) flavoring product (Reese Hickory brand) in aqueous dilutions of 4–5% (v/v) broke dormancy (40–100% germination) of both intact and dehulled red rice (Oryza sativa). To elicit this response in intact grains, the glumes had to be pricked with a dissecting needle following contact with LS and water rinsing. Germination percentages rose with increasing contact time (up to 7 d), and grains first imbibed with water before transfer to LS showed similar germination percentages as those first incubated with LS before transfer to water. LS dilutions were highly acidic (about pH 3). Dormancy-breaking activity of LS was pH-dependent and was reduced at pH values of 5–7. Buffer controls remained dormant irrespective of pH value. Maximum activity varied primarily among different bottles of LS and only to a minor extent between red rice seed lots. Dry-afterripening at 30°C for up to 14 d increased the sensitivity of unpricked, intact grains to LS compared with water controls. LS concentrations that broke dormancy of intact grains partially inhibited germination of nondormant, fully afterripened grains. Storing grains in containers of flooded soil increased sensitivity to both LS and pricking. Nitrite levels in LS were negligible and insufficient to account for the bioactivity of LS.

The effects of nitrite (NO2–) on the Nile tilapia (Oreochromis niloticus) were investigated, due to their relevance to worldwide aquaculture. Hematological parameters – functional haemoglobin (oxy+deoxy-Hb, %), methaemoglobin (MetHb%), and hematocrit (Hct) – and – plasma osmolality, plasma chloride ([Cl−]) and magnesium ([Mg2+]) concentrations – were analysed. Two experiments were conducted, each with its own non-contaminated control, 8 tilapias for each group. In experiment 1 (48 hours), and the first 48 hours of experiment 2, fish were contaminated with 0.4 mM NO2– (added as NaNO2). In experiment 2, ambient NaNO2– was removed for the second 48 hours. NaNO2– exposure increased plasma [NO2–] to 0.4 mM, which increased MetHb from 10.8 ± 2.5% to 46.8 ± 8.0%, and consequently decreased functional Hb from 89.2 ± 2.5% to 53.2 ± 8.0%. NaNO2 removal led to recovery of both parameters. Both Hct and plasma Mg2+ were lowest in fish recovering from nitrite exposure. Thus, these parameters did not show recovery. Plasma osmolality and [Cl−] were not affected by NaNO2–, probably due to the moderate rise in plasma [NO2–]. O. niloticus was thus sensitive to 48 hours of exposure to 0.4 mM NaNO2, and partially recovered from its effects after 48 hours in sodium nitrite-free water. Cultivators of Nile tilapia should thus consider the toxicity of nitrite, especially in aquaculture systems using recirculating water.

Proper estimation of the nitrogen (N) content of poultry manure and proper manure handling are necessary to ensure that application rates minimize emissions from the manure and nitrate leaching into the cropland. Uric acid and undigested proteins are the two main N components in poultry manure that cause ammonia emissions and nitrate leaching in the ground water. The ammonia that is applied to cropland may be 50 to 90% of total N, depending upon the way the manure has been stored or treated. Ammonia and hydrogen sulphide contents have been proven to be useful alternative measures of odour reduction. The order of importance in influencing ammonia formation is : litter pH > temperature > moisture content. Total fixation of ammonia was achieved below pH 4 and temperatures down 10°C are necessary to have a negative effect on degradation and volatilisation. Adsorbants such as sawdust and straw enable the capture some of the readily available N and enable the microbial population to start immobilizing N. The organic fraction of poultry manure had a C/N ratio that varied from 1 to 27:1. Most of the N (approximately 60 – 70%) excreted in poultry manure is in the form of uric acid and urea. Total N, total Kjeldahl N (TKN), organic N, ammonium, nitrate and nitrite are significantly correlated with the amount of N mineralised as well as the fraction of organic N mineralised during incubation. Some useful equations are: Inorganic N (IN) = ammonium + nitrate + nitrite; Total N (TN) = TKN + nitrate + nitrite; Organic N = TKN – ammonium or TN – (ammonium + uric acid) or TN – IN; Available N (AN) = Inorganic N + 0.4 × organic N; Predicted available N (PAN) = 80% Inorganic N + 60% Organic N.

Formalin (a 33–38% aqueous formaldehyde solution) is currently used for bath treatments to control ectoparasitic infections of fish. Its effects on nitrification were evaluated in a semi-closed pilot scale saltwater recirculating turbot culture system. Tested treatments included 1 h static exposure to 20, 30, 40, 50, 60, 70, 90 mg l−1 formaldehyde without flushing, and long-term (i.e., 2, 4 and 6 h) exposures with constant 60 mg l−1 formaldehyde in a recirculating system. Formaldehyde has no apparent effect on the ammonia oxidative bacterial community. However, a significant effect on nitrite oxidation was observed in 1 h static exposures of concentrations higher than 40 mg l−1, and in recirculating system exposures of 60 mg l−1 formaldehyde for more than 4 h. Repeated treatments may be hazardous for nitrifying bacteria, which could induce an increase in nitrite concentration. Nitrite concentrations should be monitored when treatments are repeated or when they last a long time in recirculating aquaculture systems.

In order to demonstrate the involvement of nitric oxide in the defence systems of marine bivalves, we investigated the production of superoxide and nitrite, following in vitro phorbol myristate acetate stimulation of Mytilus galloprovincialis, Crassostrea gigas and Ruditapes decussatus haemocytes. Whereas M. galloprovincialis and C. gigas haemocytes were found to produce superoxide and nitrite, R. decussatus haemocytes were found to be unable to generate either of these mediators. Nitrite is a stable end product of nitric oxide and peroxynitrite as well; it appeared therefore that some marine bivalves, to kill microbial pathogens, use NADPH-oxidase and nitric oxide-synthase pathways. This was confirmed at an experimental level where inhibitors of both enzymatic pathways blocked the production of nitrite. Moreover, this notion was strengthened by the inability of the haemocytes from R. decussatus, which cannot produce superoxide, to release nitrite when stimulated.

Based on the premise that dietary nitrate is detrimental to human health, increasingly stringent regulations are being instituted to lower nitrate levels in food and water. Not only does this pose a financial challenge to water boards and a threat to vegetable production in Northern Europe, but also may be eliminating an important non-immune mechanism for host defence. Until recently nitrate was perceived as a purely harmful dietary component which causes infantile methaemoglobinaemia, carcinogenesis and possibly even teratogenesis. Epidemiological studies have failed to substantiate this. It has been shown that dietary nitrate undergoes enterosalivary circulation. It is recirculated in the blood, concentrated by the salivary glands, secreted in the saliva and reduced to nitrite by facultative Gram-positive anaerobes (Staphylococcus sciuri and S. intermedius) on the tongue. Salivary nitrite is swallowed into the acidic stomach where it is reduced to large quantities of NO and other oxides of N and, conceivably, also contributes to the formation of systemic S-nitrosothiols. NO and solutions of acidified nitrite, mimicking gastric conditions, have been shown to have antimicrobial activity against a wide range of organisms. In particular, acidified nitrite is bactericidal for a variety of gastrointestinal pathogens such as Yersinia and Salmonella. NO is known to have vasodilator properties and to modulate platelet function, as are S-nitrosothiols. Thus, nitrate in the diet, which determines reactive nitrogen oxide species production in the stomach (McKnight et al. 1997), is emerging as an effective host defence against gastrointestinal pathogens, as a modulator of platelet activity and possibly even of gastrointestinal motility and microcirculation. Therefore dietary nitrate may have an important therapeutic role to play, not least in the immunocompromised and in refugees who are at particular risk of contracting gastroenteritides.

Addition of 2 mM nitrite or ammonium to aerobically incubated cultures of Gloeothece rapidly inhibited N2 fixation (measured as acetylene reduction). In contrast, 2 mM nitrate inhibited N2 fixation less rapidly and less extensively, and often temporarily stimulated nitrogenase activity. The inhibitory effects of both nitrate and ammonium could be prevented by addition of 3 mM L-methionine-DL-sulphoximine, suggesting that the true inhibitor of N2 fixation was an assimilatory product of ammonium rather than either ammonium or nitrate itself. The inhibition of N2 fixation by nitrite could not, however, be prevented by addition of L-methionine-DL- sulphoximine. On the other hand, nitrite (unlike nitrate and ammonium) did not inhibit N2 fixation in cultures incubated under a gas phase lacking oxygen. These findings suggest that the mechanism whereby nitrite inhibits N2 fixation in Gloeothece differs from that of either nitrate or ammonium. The inhibitory effect of nitrite on N2 fixation did not involve reduction of nitrite to nitric oxide, though nitric oxide was a potent inhibitor of nitrogenase activity in Gloeothece. Nitrate and nitrite inhibited the synthesis of nitrogenase in Gloeothece, while ammonium not only inhibited nitrogenase synthesis but also stimulated degradation of the enzyme. In addition, all three compounds favoured the appearance of the Fe-protein of nitrogenase in its larger, presumed inactive, form.